I don't know specifics about Indiana, but usually you are good to go once you have a state cert. From what I've seen, the NREMT usually helps you get a state cert, but isn't usually good on its own. My recommendation is to apply for jobs or call different agencies/companies you are interested in to see what is required to work there. Sometimes companies will require more than a state cert anyways and sometimes requirements vary by agencies/companies. Some companies may want to exceed the minimum standard that the local government has.